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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

Status Report on the Review of the Santa Susanna Field Laboratory (SSFL) Site 

Profile, SEC Petition, and SEC Petition Evaluation Report

Prepared for the SSFL work group meeting in Cincinnati, Ohio, April 20, 2010

Prepared by SC&A, Inc.

April 15, 2010

In anticipation of the upcoming SSFL working group meeting in Cincinnati, this report 

presents a summary of the status of issues that are currently under active discussion and 

investigation for the SSFL site profile, SEC petition, and SEC petition evaluation report. 

The report also introduces several new issues that have emerged since the last working 

group meeting on April 17, 2009.

The issues that are under active discussion and investigation are embedded in seven 

action items that were assigned to NIOSH at the conclusion of the April 2009 working 

group meeting. That is, each of the seven action items relate to one or more issues 

contained in the SEC issues resolution matrix for SSFL. Those issues have, to varying 

levels, been addressed in the latest update to the matrix, which will be available to the 

Board and working group for the April 20, 2010 meeting. 

The NIOSH action items from the last working group meeting include the following:

1. Start date for nuclear activities [Items 9 (SC&A #1) in issues matrix] – Review of 

the activities at Atomics International sites from 1953 - 1955 to establish the start date

and update the TBD as needed.

a. Status: NIOSH has cited detailed historical facility descriptions from Sapere 

and Boeing (2005) in the SSFL issues matrix. A review of Sapere and Boeing 

(2005) indicates that pre-1955 activities consisted mainly of design and 

construction operation. Further, there is no indication that radiological 

operations took place before 1954. Thus, SC&A believes that this issue is 

resolved.

2. Sodium Reactor Experiment (SRE) incident (Item #1 in issues matrix) – A 

contractor will perform an independent review of different release estimates resulting 

from the SRE incident in 1959 to determine the most scientifically defensible release 

scenario and, therefore, the extent and the necessity of an exposure model for on-site 

workers. The TBD is to be revised to contain additional detail of the incident and 

potential exposure implications.

a. Status: It is our understanding that the 1964 SEC cutoff date and expanded 

class definition to encompass all workers in Area IV renders the issue of 

internal exposures from the SRE incident moot. Presumably, the external 

coworker model would cover non-presumptive claims during the SEC period. 
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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

Inquire into the status of the independent review and TBD update in light of 

the new cutoff date.

3. Internal coworker model [Item #10 (SC&A #2) in issues matrix. Impacts issues 

4, 6, 10, 11] – NIOSH is to develop an internal dose coworker model that 

encompasses certain incidental exposures, such as potential exposures resulting from 

sodium disposal facility (burn pit) activities.

a. Status: The NIOSH internal coworker model is still under development. 

NIOSH has provided a justification for the SEC cutoff date of December 31, 

1964 that is based principally on limitations of the internal coworker model 

database for earlier dates (missing positive bioassay results). 

4. Tritium plume [Items 3 and 12(2) in issues matrix] – This is one aspect of the 

environmental exposures issue. Workers may have been exposed to drinking water 

contaminated with tritium from reactor operations. NIOSH was to prepare a white 

paper describing their model and base data for estimating dose to workers from 

ingestion of tritium-contaminated drinking water.

a. Status: Information on the tritium plume was initially to be presented in a 

NIOSH White paper. However, NIOSH instead included the information in 

its entirety in the issues matrix. Based on more recent well monitoring data 

and the argument put forth by NIOSH in the issues matrix, we believe this 

issue to be resolved. Specifically, we concur that the NIOSH model for the 

tritium plume is sufficiently claimant favorable, given the measured 

contamination levels at the various wells, model assumptions, and the very 

small likelihood of drinking water aquifer contamination (i.e., up-gradient 

location of drinking water wells from Building 4010 and remote likelihood of 

a connection between superficial and deep aquifers). Note that doses are 

small (nominally 4 mrem/yr from ingesting 2 liters per day at 20,000 pCi/l), 

but must nonetheless be considered in dose reconstruction.

5. Lack of information on environmental exposures (Item #12 in issues matrix. Also 

impacts issue 5) – NIOSH was to re-evaluate their current approach of backextrapolating stack emissions data collected from 1971 to 1999 to early periods. 

Back extrapolation is likely to underestimate stack emissions for years 1954 through 

1970 due to the steady reduction in facility operations over time. For example, 

nuclear reactor programs were essentially phased out in the early 1970s. As of May 

2009, TBD-4 was undergoing revision to include new information discovered during 

SEC research.

a. Status: NIOSH has indicated that revisions to internal, external and 

environmental TBDs are in the completion stages but that these revisions were 

minor and only done to include SEC language. Inquire into the status of 

this specific re-evaluation and TBD update
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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

6. External dose coworker model [Item #13(1) (SC&A #5) in issues matrix. 

Impacts issues 6, 7, 8, 11, 13 (2)] for all four Atomics International sites to be 

finalized and released

a. Status: The external coworker model was released on August 3, 2009. See 

findings from SC&A review of the model and supporting data in the set of 

new issues since April 2009.

7. External dose coworker model as regards neutron dose methodology [Item 

#13(2) (SC&A #5) in issues matrix]. Neutron dose methodology was to be 

reassessed and the associated TBD revised. In the absence of empirical data 

involving neutron spectra for reactors and Pu fuel storage facilities, the lack of 

dosimeter calibration methods, and the relative insensitivity of NTA film to neutrons 

with less than 500 keV (or as much as 1 MeV), there remains an undefined level of 

uncertainty for recorded neutron doses. 

a. Status: NIOSH has indicated that a white paper on the NTA film issues is 

currently being developed and is in the completion stages

The one SC&A action item was to provide NIOSH with excerpts from a notebook from 

an employee of the Canoga Avenue facility. That document was provided to NIOSH 

shortly after the April 17 2009 meeting.

New issues that have emerged since the last working group meeting in April 2009 

include:

1. Issues identified by SC&A in our review of ORAUT-OTIB-0077 and its supporting 

data [the NIOSH external dose coworker model for the four Atomics International 

(AI) sites]. In February 2010, SC&A issued a draft report to the SSFL Work Group, 

which contained a critical review of NIOSH’s proposed external coworker model. 

Specifically, SC&A’s review focused on the suitability of the database selected by 

NIOSH for use in its coworker model. The SC&A review, entitled “Review of 

Database Used to Develop ORAUT-OTIB-0077: External Coworker Dosimetry Data 

for Area IV of the Santa Susana Field Laboratory, the Canoga Avenue Facility 

(Vanowen Building), the Downey facility, and the De Soto Avenue Facility 

(sometimes referred to as Energy Technology Engineering Center [ETEC] or Atomics 

International”, will be available at the work group meeting to help facilitate 

discussion of issues that the Board or the working group might have. 

For its coworker model, NIOSH employed a database that was compiled by Boice et 

al., (2006) for a retrospective epidemiologic cohort mortality study entitled Mortality 

Among Radiation Workers at Rocketdyne (Atomic International) 1948–1999. This 

database represented external lifetime exposures by year for 5,743 radiation workers 

who were employed for at least six months at the Rocketdyne (Atomic International 

(AI)) facilities in the years 1948 to 1999. In behalf of the study’s objectives, the 
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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

database included worker exposures at other facilities either before and/or after their 

employment at Rocketdyne/AI.

As pointed out in our review, while the integration of pre-Rocketdyne/AI, 

Rocketdyne/AI, and post-Rocketdyne/AI exposures is technically sound for the 

epidemiologic mortality worker study that required estimates of lifetime occupational 

doses, use of these data for a SSFL coworker model is inappropriate.

In our draft report, SC&A identified the following five (5) issues/deficiencies that, in 

its current state, preclude the use of this database for the SSFL coworker model:

Issue #1: NIOSH may have misinterpreted worker dose data labeled “Total External 

Dose” by Boice et al. to mean the sum of photon and neutron doses. Our 

review shows that the “Total External Dose” does not include neutron 

exposure. This deficiency can be corrected.

Issue #2: Termination dosimetry data was misused. Termination dose data may 

frequently represent the cumulative dose received over many years and, 

therefore, cannot be assigned to a single year. SC&A identified termination 

doses in excess of 60 rem that were assigned to a single year for some 

workers. In many cases, the termination doses were assigned to periods 

several years before or after the worker’s actual period of employment as 

SSFL. This deficiency can be corrected.

Issue #3: NIOSH included annual exposure data associated with multiple/unspecified 

non-SSFL facilities, which may not comply with the surrogate data criteria 

specified in OCAS-IG-004. Many or these were termination doses assigned to 

a single year. This deficiency can be corrected.

Issue #4: NIOSH may have misinterpreted “Blanks” in the database resulting in the 

potential for unaccounted doses for individual workers. The issue of whether 

workers with potentially incomplete monitoring data can serve as 

members of a coworker model that, in turn, provides surrogate data for 

their incomplete monitoring data may not be readily reconciled.

Issue #5: Neutron exposures may either have been totally ignored (as alluded to in 

Issue #1 above) or substantially underrepresented since no attempt was made 

to account for NTA dosimeter deficiencies and revised neutron quality factors 

suggested by ICRP-60. This deficiency can be corrected.

In addition to the issues regarding the external coworker database, SC&A has identified 

several issues related to the model itself, which are summarized in an SC&A 

memorandum dated November 4, 2009, entitled “Resolution of the SSFL Site Profile and 

SEC Issues Matrices.” The summary conclusions of SC&A’s review of the model are 

provided below:
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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

Our review of the SSFL coworker model for the assignment of external dose identified the 

following potentially significant deficiencies. For select cancer sites, a substantial 

fraction to the total external dose may involve the contribution of non-penetrating 

radiation. Currently, Tables 2 and 3 of OTIB-0077 are based solely on dosimetry data 

that exclude measurements of the shallow dose.

Another finding involves NIOSH’s use of annual worker doses that include neutron 

exposures. NIOSH’s simplified approach of collating the restrictive number of reported

worker-neutron doses with the larger number of reported worker-photon doses has the 

effect of diluting neutron doses for the subset of SSFL worker assigned to reactor, fuel 

storage, and accelerator facilities. Equally, NIOSH’s use of the reported neutron doses 

at face-value fails to account for deficiencies of the NTA neutron dosimeters as explained 

in bullets 2, 3, 4, and 5 above.

Finally, NIOSH has recently provided SC&A with the data that was used to develop the 

coworker model. We are currently working with NIOSH to better understand the data 

that was used to confirm that it is appropriate for the development of a coworker model. 

We will continue this review with the approval of the Work Group

As noted above in the summary conclusions, the memorandum was issued before SC&A 

conducted a review of the supporting data. Thus, the statements regarding collated 

neutron and photon dose do not reflect Finding #1, regarding NIOSH’s misinterpretation 

of “Total External Dose.”

2. Potential impacts of SC&A’s findings in behalf of the external coworker model 

on the 1964 cutoff date for the Area IV and DeSoto SECs. The cutoff date for the 

Area IV SEC was extended to the end of 1964 (effective May 5, 2010) based 

principally on data limitations (missing positive bioassay values) for the years 1961-

1964. The same cutoff date is applied to the proposed DeSoto SEC for the same 

reasons. The findings of our review of the Boice database as applied to the external 

coworker model may impact this cutoff date, which was based in part on the 

presumption that the external model and underlying data were robust. Similarly, 

deficiencies identified for the SSFL external coworker model may also apply to the 

proposed internal coworker model.

3. Free movement in and out of Area IV by Rocketdyne personnel. This topic was 

discussed at length at the full Board meeting in February 2010 (pp 244 -254). In 

summary, due to poorly defined boundaries, a lack of administrative control of 

personnel movement into and out of Area IV, and the potential spread of 

contamination beyond area IV, some Rocketdyne workers were likely exposed to 

radionuclides originating in Area IV but were not monitored. Further, available 

records are not adequate to characterize spatial and temporal exposure parameters for 

this class of workers for the purpose of dose reconstruction. 

In NIOSH’s April 15 update to the work group, they state: 

“Based on discussion during the February board meeting, NIOSH has looked into 

the issue of site coverage, but has not been able to identify any pertinent 
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NOTICE: This September 2014 version of the issues matrix is cleared for public release. Note, however, that future versions of this 

matrix will not be freely distributed to the public until further reviews for Privacy Act-restricted information are conducted.

information that would indicate that DOE related nuclear activities were carried 

out in areas other than Area IV at Santa Susana Field Laboratory.”

This response does not adequately address the concerns voiced at the full Board 

meeting because the issue is access control to radiological areas inside Area IV and 

not whether DOE activities took place outside Area IV.

4. The petition evaluation reports (PER) for the Canoga, Downey and DeSoto 

facilities. While SC&A has not been tasked to review these SEC petition evaluation 

reports, we believe that a discussion of them would be beneficial.